A customer prepares to sign a credit card slip at a Target store on December 19, 2013 in Miami, Florida. Target announced that about 40 million credit and debit card accounts of customers who made purchases by swiping their cards at terminals in its U.S. stores between November 27 and December 15 may have been stolen.
Joe Raedle/Getty Images

The breach affects Target shoppers who swiped their credit or debit cards at U.S. stores between November 27 and December 15. The crooks who gained access to Target's database may now possess names, credit card numbers, expiration dates and security codes for those shoppers.